i spoke with cnn contributor, former cia officer bob baer and dr. sanjay gupta. we talked about this last night, but explain again what one warhead filled with sarin could do. >> one of these shells and the standard shell the syrians put this in is a 122 millimeter shell, a standard artillery piece. if they were to drop this into a dense area, into damascus or a suburb of homs, it doesn't matter which town, it will instantly kill 18,000 within the first few minutes. >> from one shell? >> one single shell would immediately kill 18,000 people. you know, this is a liquid. it's dispersed. it sticks on you. you get a few -- a little bit in your system, and you're dead. >> sanjay, what does it do to somebody who comes in contact with it? >> it affects receptors in the brain, and let me preface it by saying it's odorless and tasteless and it's colorless. it's hard to even know, you know, that it's there because of those things. also by touching it as bob was talking about, but also by inhaling it or eating food or drinking water contaminated with it, you can also get po